1. Field of the Invention
The present invention relates generally to the field of wiring systems, such as for programmable logic controllers used in industrial automation applications. More particularly, the invention relates to a technique for electrically coupling electrical devices within a panel or enclosure, such as programmable controller input/output modules, to external circuitry, such as input and/or output devices.
2. Description of the Related Art
A programmable logic controller (PLC) typically includes a processor module and several input/output (I/O) modules. The I/O modules are used to couple the processor module to input and/or output (I/O) devices. Input devices provide electrical signals to the PLC. The electrical input may be used to provide the processor module with a variety of information. Output devices receive electrical output from the PLC. The PLC uses the electrical output to control the operation of the output device, such as for regulating various industrial, material handling, process, or other operations.
Typically, a processor module and several I/O modules are housed in a sealed enclosure. Additionally, in a typical application, the I/O modules are coupled to a distribution block for routing to a plurality of I/O devices. An electrical cable is routed between the I/O modules and a distribution block through an opening in the enclosure. A seal may be formed around the electrical cable to prevent water or other contaminants from entering the enclosure. However, hard wiring the electrical cable to the I/O modules and passing the electrical cable through the enclosure may require an electrician or otherwise trained technician. This may increase the time and expense of installing a system utilizing a PLC.
Moreover, where wiring is installed with and extends from this enclosure, re-wiring may sometimes be needed. For example, if the power and data conductors of a wiring bundle become damaged or severed, the entire cable may require replacement. This operation, again, can be time consuming, resulting in additional expenses for service personnel and downtime for the PLC and any controlled equipment.
There is a need, therefore, for an improved technique for electrically coupling electrical, panel-mounted devices, such as PLC""s to external devices. There is, in particular, a present need for a technique to enable a customer to electrically connect a PLC to a distribution box or an I/O device without permanent hard wiring.
The present invention provides an electrical coupling technique designed to respond to these needs. According to one aspect of the technique, a protective enclosure to house a PLC is featured. The protective enclosure has a through-panel connector. The through-panel connector has a connector portion that is configured for mating engagement with an electrical cable that is electrically coupleable to a PLC input device or a PLC output device. The PLC is electrically coupleable to the through-panel connector. The through-panel connector enables the electrical cable to be electrically coupled to the PLC without permanently hard wiring the electrical cable to the PLC or having the electrical cable penetrate the enclosure.
According to another aspect of the present technique, a through-panel connector for a PLC is featured. The through-panel connector comprises a first electrical connector and a second electrical connector. The first electrical connector and the second electrical connector are electrically coupled to one another. The first electrical connector is used to couple an internal cable from an I/O module to the through-panel connector. The second electrical connector is used to couple an external cable to the through-panel connector.
According to another aspect of the present technique, a method of electrically coupling a PLC housed within an enclosure to an electrical apparatus is featured. Additionally, a method of assembling a PLC within a protective enclosure also is featured.